https://lolibooru.moe/ - almost all loli
https://yande.re/post - a mix of loli and reg
https://gelbooru.com/index.php?page=post&s=list&tags=all - a mix of loli and reg, need to turn on the loli stuff via https://gelbooru.com/index.php?page=account&s=options and you don't even need to make an account
https://chan.sankakucomplex.com/ - a mix of loli and reg don't know about this but @Gen. Lolicon like it, tho you need an account
https://www.pixiv.net/ - a mix of loli and reg and you'll need a account (where most of loli and reg hentai come from, this website is so good)
https://tbib.org/ - a mix of loli and reg
https://booru.allthefallen.moe/ - almost all loli and need a grain of salt
https://rule34.xxx/ - almost all reg and you need to know of a loli char, no loli tag
https://rule34.paheal.net/post/list - almost all reg and you need to know of a loli char, no loli tag and needs a need a grain of salt
https://booru.allthefallen.moe/ - pretty much all loli, pretty much western style lolis, they also have a forum, modding and many other stuff related to lolies
https://luscious.net - mostly regular but lolis can be found
https://pomf.tv - livestream service with no limitation, hence a lot of people drawing lolis
https://baraag.net - no limitation, a lot of lolis. It's where all the artist post their uncensored stuff. it's kinda like https://mastodon.social and i think is the same website but use Baraag to make it easier for you.
https://exhentai.org - lolis and regular can be found but getting access to this site is weird ( i explain how to log in below )
https://e-hentai.org - lolis and regular
https://nhentai.to - lolis and regular
https://imhentai.xxx - lolis and regular
https://kemono.party - used to bypass Patreon, Pixiv, Fanbox, Gumroad, SubscribeStar, DLsite, Discord, Fantia. You can find lolis
https://twitter.com - you'd be surprised but yeah, might need an account saddly
https://safebooru.org - loli and reg
http://roriland.info - loli and loli games
https://xbooru.com reg and a bit of salt
https://nozomi.la - loli and reg
https://hitomi.la - loli and reg
https://konachan.com - loli and reg
https://nijie.info - loli and reg, might need to log in tho
https://impervert.com - some loli mobile games
https://loudbooru.com - loli and reg...
https://exhentai.org - a very good website that contains everything you're looking for. Not joking, it's that good. Exhentai is the premium version of https://e-hentai.org wich doesen't contain lolis. To access Exhentai, you need to create an account at https://forums.e-hentai.org. Then you just wait few days and you'll get access to Exhentai. And note that you won't be able to access the website you delete your cookies, use a vpn or go in private search, it won't work otherwise
https://rule34hentai.net - loli and reg
BONUS
here's some reverse image search websites you can use to find the sauce on certain images
https://saucenao.com
https://trace.moe/
https://yandex.com/images/
https://www.bing.com/images/search?q=0&form=HDRSC2&first=1&tsc=ImageBasicHover
https://images.google.com/
https://iqdb.org/
https://ascii2d.net/
https://tineye.com/
https://imgops.com
Do note that saucenao is the one you might want to use the most, it's made to find the sources of nsfw images
I hope that all this will help you in your journey, sorry if i made some writing mistakes my english is not perfect :)
-Tower